It's no secret, smoking is injurious to health and now researchers have found that it also plays a direct role in the development of schizophrenia.

Smoking may be a factor for developing psychotic illness such as schizophrenia, scientists suggest. According to the team at King's College London, smokers are more likely to develop the disorder and that too at a younger age.

The researchers' studies suggest nicotine in cigarette smoke may be altering the brain.

"Pretty strong case" but needed more research," experts said.

Smoking's association with psychosis is not a recent one. It has often been believed that schizophrenia patients tend to smoke because they use cigarettes as a form of self-medication to ease ache caused by hearing voices or having hallucinations, according to records on BBC.

The team analyzed data encompassing 14,555 smokers and 273,162 non-smokers.

The study indicated the following:

57% of people suffering with psychosis were already smokers at the time they had their first psychotic episode.

Those who smoke daily were twice as likely to develop schizophrenia as compared to non-smokers.

Smokers developed schizophrenia a year earlier on average. The claim is that if there is a higher rate of smoking even before schizophrenia is diagnosed, then smoking no longer remains a simple case of self-medication.

That being said, not all smokers develop schizophrenia; however the researchers believe it is increasing the risk.

The findings, however cannot prove causation, and the researchers note that some of the studies they looked at didn't take into consideration possible confounding factors including whether smokers were also regular cannabis users, something which is linked with psychotic illness, The Independent noted.

Dr James McCabe, clinical senior lecturer in psychosis studies at the King's Institute of Psychiatry, Psychology and Neuroscience (IoPPN) said smoking should be "taken seriously as a possible risk factor" for psychosis and not "dismissed as a consequence of the illness."

Smoking tends to impact on levels of the chemical dopamine in the brain, which too plays a role in psychotic illness, researchers suggested.

"Excess dopamine is the best biological explanation we have for psychotic illnesses such as schizophrenia. It is possible that nicotine exposure, by increasing the release of dopamine, causes psychosis to develop," Sir Robin Murray, professor of psychiatric research at the IoPPN said.